Production of cinematograph film positives



p 1932- J. E. THORNTON 1,879,775

PRODUCTION. OF CINEMATOGRAPH FILM POSITIVES Filed April 12. 1929 2Sheets-Sheet l Sept. 27, 1932. J. E. THORNTON PRODUCTION OFCINEMATOGRAPH FILM POSITIVES Filed April 12, 1929 2 Sheets-Sheet 2Patented Sept. 27, 1932 UNE'EED STATES JOHN EDWARD THORNTON, or en.BR-ELADE, JERSEY, CHANNEL ISLANDS, AssIGNoR PATENT err-Ice- TO JOHNO'WDEN OBR-IEN, 0F MANCHESTER, ENGLAND PRODUCTION OF CINEMATOGRAPH FILMPOSITIVES Application filed April 12, 1929, Serial No. 354,714, and'inGreat Britain April 25, 1928.

This invention relates tothe production of cinematograph film-positivesby prlnting upon opposite sides of a transparent film a pair ofcomponent images of two different and absorb the dye upon and into itssurface,

or into a layer formed upon such surface, the operation being assistedif necessary by the use of suitable mordants applied to or com: binedwith the surface of the film to be printed upon. The images are of thefull-tone variety which means that the gradations are formed withoutdots, lines, or grains.

State of the art A method of printing two images simultaneously inregister upon opposite sides of a single strip of transparentcinematograph film was first described in my specification No. 1,250,718which has in practice proved a very successful method and has for a long-T it was also suggested that the two images could be formed uponnon-sensitized film by photo-mechanical or imbibition printing methodswithout light.

But whilst the photographic method J T proved satisfactory in practice,because sensitiz-ed filmis'always printedand registered by step by stepmethods one picture at a time, and therefore "presented no registrationdifliculties, the photo-mechanical printing methods could not besuccessfully carried out be cause off-registration difficulties. Theseare due in thefirst place to the fact-that a prolonged period of contactis necessary for photo-mechanical imbibition printing, and therefore, inthe second place,it is necessary to print a number of pictures at a timeto secure a sufiiciently reasonable rate of output to make the processof any value commercial- 1y. In the third place, owing to the difference in length of the printing belts or negatives and the dry blankfilm, perforations if made in the film would not coincide withperforations of the same pitch gauge made in the printing belts, andtherefore no means of accurate registration was known at that timeor'disclosed by the paragraph which suggested the use ofphoto-mechanical printing,v

Since that date considerable attention has been devoted by variousresearch workers to discovering some means for overcoming theregistration difficulties in printing by photo mechanical or imbibitionmethods. And it has been proposed, for producing one set of images on afilm or two sets superimposed upon the same side of the film, to stretchthe negative or the film or both bands until they become the same lengthand their perforations thus made to coincide before printing the images,and in that way attempt to secure accurate positioning and registration.

That method is however very diflicult and uncertain in its results, aswill be understood when it is stated that a difference of 1/1000 of aninch in registration of two component images suffices to make theprinted film useless, owing to the great displacement visible T bepresent invention The present invention, among other features, dealswith this registration difficulty in a very simple manner viz :byomitting the perforations altogether from the film, printing the twocomponent images simultaneous- 1y upon opposite sides of the blanknon-perforated film, then adding the perforations after printing, and insuch manner that the loss or gain arising from the difference in lengthbetween the printed film and printing belts or negatives is distributedin the space between each picture throughout the whole length of film.

Therefore, instead of the pictures being placed on the film to suit thelocation of the perforations of the negative as in printing onsensitized film, on the contrary in this in.

vention the method is entirely reversed and the perforations are made inthefilm to suit the location of the pictures on the film. They may beplaced by visual methods controlled byan'operator, or automatically by aperforating machinecontrolled indirectly by the printing belts,-or byboth in combination as will be hereinafter described.

' This new system of printing on blank nonperforated film, andperforating afterwards, forms the key to the successful production ofcinematograph films printed by photo-mechanical means.

The process as a wholetherefore comprises the following features incombination '1. The two printing-belts are each provided withperforations which are coincident in each pair of component images.

These perforations are used for registering the belts and also fortraction purposes.

2. The two belts, and therefore the two' images, are accuratelyregisteredsimultaneously exactly opposite each other, by registeringapparatus which comprises two intergeared or interlocked sprocket wheelsor drums, the teeth of which exactly fit the perforations of the twobelts.

3. The blank film itself has no perforations and is not itselfregistered either with the belts, images or sprocket apparatus, butmoves longitudinally quite freely.

4. The two images are printed upon oppo-T site sides of thenon-perforated blank film simultaneously by pressure alone.

5. The printing impression is made by nipping the blank film between thetwo printing belts when the two component images upon them have beenbrought and placed by the sprocket teeth and perforations exactlyopposite each other.

6. The printing operation is completed by maintaining all three bands inclose intimate contact over a prolonged period which is sufficientlylong to completely lift or extract the color from the printing belts andallow it to be absorbed by the film, and whilst the three bands arestill moving forward under thepressure contact of a series of gearedpressure rollers between which the bands in their forwardmovement pass.

7. The perforations are made in the film after printing, and in suchmanner that loss or gain in length of the film as compared currentspecification and claims Serial No. 366,743 filedMay 28, 1929, howevermechanism for producing the continuous film will now be described withreference to the accompanying drawings r Fig. 1 is a side elevation ofmachine for printing simultaneously by photo-mechanical or imbibitionprocess upon opposite sides of a transparent film a pair of componentimages of two different colors without sensitizing and without light.

Fig. 2 is a sectional View of the gearing for the sprocket wheels andpressure rolls.

Fig. 3 is a detail view of registering sprocket.

- Fig. 4 is a detail view of drive for same.

Fig. 5 is a detail view of a modified form of registering sprockets.

The film' is registered and printed in a machine comprising a fixedframe A carrying a number of rollers A arranged vertically one above theother and a movable or floating frame B carrying a corresponding numberof rollers B The floating frame B is mounted on bearing rods or supports6 so that it can move laterally and is controlled by the two pivotedbell crank levers C which carry adjustable weights W to maintain uniformpressure between the rollers A and B even though the film strip 1 andthe printing belts 2 and 3 passing between the rollers should vary inthickness, which variation might be from 1/1000 to 3/1000 of an inch.

Above the top rollersof the series A and B are arranged two sprocketwheels D D an ranged a little distance apart and having their teeth dspaced to correspond exactly with the spacing of the registrationperforations in the printing belts 2 and 3. The printing belts 2 and 3are held down on to the teeth (5 of the sprocket wheels D and D by theweighted pivoted levers d and (Z which carry flanged rollers d theflanges of which press on to the surface margins of the belts betweenthe sprockets thereby holding the belts down to the root of the teethand keeping them quite taut. V

The two sprocket wheels D D are driven from a common shaft and aregeared together by the gear wheels 6 6 so that the.

wheels D D will rotate in unison with out there being any backlashbetween them,

int

imageson opposite sides of the film-so that the two series of images mayexactly coincide on the finished film. v Each of the rollers A and B isalso posii tively driven (see Fig.2) by skew gearing e from the verticalshafts E and E The shaft. E is driven through bevel or other suitablegear 6 from the shaft carrying the sprocket wheel D and the shaft E isdriven by similar gear 6 from the shaft carrying the sprocket wheel D 7Thus the sprocket wheels D and D and the rollers A and B are'all gearedtogether and are driven at the same surface speed, so

i that after the belts 2 and 3 have been accurately registered by thesprockets, they will remain in such accurate register unt1l they and thefilm emer e from the last air of "roll 7 printing belts 2 and darepressed into contact therewith as the three bands. enter the nip of thefirst pair of'rollers A B After emerging from the series of pressurerollers A B the printing belts 2 and 3 pass-over tractor sprocket wheelsG being kept in contact therewith by weighted rollers g and then passover and under the rollers h. of the dyeing apparatus H any or all ofwhich rollers are positively driven; The

belt leaves the dyeing apparatus, between the V rollers 7L1 and if whichserve to remove the surplus dye from the belt. The belts 2 and 3thenpass up and down over the rollers H before passing back to thesprocket D ar-. ranged immediately in front of the correspondingregistration sprocket D or D The sprocket wheels G, the rollers h of thedyeing apparatus H and the sprockets D are all preferably driven throughgearing from the main driving shaft so that they all roe centric plungertype having four perforating punches at each edge of the film. It isdriven through gearing as shown 1n Flg. 2 from the driving shaft E Theperfo-rator is so geared to the shaft E that it makes one punchingstroke for each picture space on the film. The film 1 is positioned inthe perforator J by the feed claw J of known type which has a to and froand an up and down movement and is actuated by an essentric j geared tothe perforator J so that the Claw lg-makes 1 stroke for each pictureSpace .0 the film. i I a .As theperforator J and the feed claw J 2 aredriven from the driving shaft E the perforations in thefilm willcorrespond with the perforations in the printing belts 2 and 3 so thatafter an initial adjustment of the contraction orexpansion in the filmrelative to theprinting belts and such difference in length of the wholefilm will be evenly distributed between each pair of adjacent pictures.-V w Guides and guide rollersare fitted at the topand bottom of themachine to prevent lateral displacement of the unperforated film' duringprinting and perforating.

After being perforated the film 1 passes over the sprocket K to thefinishing bath K? where it is treated in known manner with V hardening,flexing, orvarnishing agents. The film then passes through the dryingchamber K being led up and down therein over the rollers 70 arranged atthe top andbottom. The drying chamber is supplied with hot air whichenters at the bottom through the pipe k and after absorbing moisturefromthe film leaves the chamber through the outlet pipe 70 at the top of thechamber; or it may enter at the topand exhaust from the bottom. V i Thefinished film after passing through the drying chamber K fis finallywound on to the reel or spool K 7 A modification of the sprocketregistering device for the belts 2 and 3 is shown in Fig.

5 which arrangement is however only applicable where the belts are ofgreater width than thefilm 1 and have their perforations in the marginsoutside the film. In this arrangement the teeth of (Z of one sprocket Dfit into holes (Z in the other sprocket D and the teeth d of thesprocket D fit into holes 0Z in the sprocket D thus the perforations ofthe belts are engaged alternately by the teeth of the two sprockets.This arrangement ensures accurateregister of the two belts but in manycases is not as convenient an arrangement for obtaining accurateregister as the arrangement described above with reference-to Fig. 1.

The non-perforated bZa/nk film ing to the particular dyeing methodused.

its

F or example, both sides may be coated with an adhesive substratum ofthe usual type and then each againcoated with a layeryof, ab-

sorbent colloid, such as gelatine, andthe:

material itself if dyes of a suitable class are used capable of dyeingthe'material used for the transparent film. For example, some dyes aresuitable for dyeing nitro-cellulose (celluloid) film and othersaresuitable for dyeing cellulose-acetate film. Either of these or otherpreferred forms of transparent cellulose material may be used, includingalso the new laminated films which have a centralcore ofnitro-celluloseand two outer face-layers of acetate-cellulose.

. The printing belts I The printing belts may be of any suitablematerial, for example strips of ordinary film-' material, or thick bandsof celluloid, or ofmetal, or even of paper, ora built-up series likewaterproofed with cellulose varnish and asuitable adhesive substratum(both grain ing and substratum being of known type),

and thenapplyingthe gelatine or other colloid layer by coating a fluidsolution thereof on to thesubstratum, either as oneor more coatings orlayers, or as a single. coating or layer.

The printing image is formed upon each belt by sensitizing the gelatineor other colloid layer with a bichrornate salt or with a silver saltmade up as a gelatine emulsion, then printing the sensitive belt bylight under a suitable negative or positive according to the type ofimage required, and subsequently developing and treating the images insuch manner that parts of each-image aredyeabsorbent and parts become sohardened that;

they are dye-resistant All these are well-.' known processes.

The printing-images have one image of the pair reversed in relation tothe other image.

According to the type of printing belt re quired and thedyeing processto be employed, the images aremade either of flat planographic,orrelief, or intaglio description, and either negative or positive incharacter. 7

The several methods are as follows (A) The clich-images are of negativecharacter formed of soft and hardened gelatine, the soft gelatine partsof each image receiving the applied ink or dye and the hardened part-srejecting it. These clicheimages will be of fiat or planographiccharacter.

(B) The clichdmages are of positive char-' acter formed entirely ofhardened gelatine (left after dissolving away the soft parts), the inkor dye being applied to the relief parts. These cliche-images will be ofrelief character.

C) The cliche-images are of intaglio positive character. the depressionsof the positive being formed by dissolving and washing out the softgelatine, leaving the hardened gelatine of theclich-image to form acolor-hold- V I ing container to be filled up level to itstop surfacewith color. The color or dye is thickened by mixture with a glutinousfiller such asstarch, gum arabic, gum tragacinth, algin, or anequivalent to keep it from inadverently running out of the intaglio,image. The surplus color is removed by the usual ductor knife or scraperbeing passed over the level surface of the cliche. These cliche imageswill be of intaglio character.

All these methods of printing are more or less known, and by variousnames such as imbibition, hydrotypedye-printing, and intaglio-printing.

Printing and registering the images Transfer of the dy from theprinting-belt on to and intothe film-surface is eifected bypressure-contact, the duration of such contact being dependent firstlyupon the type of printing-image (flat, relief or intaglio), secondlyupon the class of dye used, and thirdly upon the relative conditions ofthe colloid on the film and the colloid on the printingbelt. By somemethods very rapid transfer of dye can be secured, but by othermethodsthe transfer isjmuch slower, requiring prolonged contact to extractsufficient dye from the printing belt and to absorb it sulficient'lyinto the film-colloid.

Most of these varying factors are known to those skilled in thisparticular art, but are described in order to make the descriptioncomplete for the whole process of producing a film according to thisinvention.

eams The main points of the invention comprise two principal featuresviz (1) Simultaneously transferring andabsorbing from twoprinting'belts, two component images of one picture, each of a differentcolor, on to and into two absorbent surfaces upon the opposite-sides ofa single transparent film, so that the two dyed impressions are locatedback-to-back on the-one (2) Securing absolutely accurate register of thetwo component images of the same picture by holding one of the componentprinting images by oneregisteringapparatus and holding the othercomponent printing image by another registering apparatus; the tworegistering apparatus being driven from'a common shaft through worm orbevel gearing so that they will move in unison, or when the printingbelts are Wider tha'n'the film and have their perforations outside theedges of the film, the two registering apparatus may be so constructedthat they interlock at the impression period, when the two printmg beltsand the film to be printed are so positioned that all three are squeezedtogether to effect the initial act ofimpression transfer.

In previously known and used methods of printing two dye-impressionmages it has been thecustom to make the first series of impressions onthe film and then print the second series superimposed upon the first'bya second impression.

When a long contact between the printing belts and the film is necessary(as in the printing method A described above) when'the printed filmleaves the prlnting' belt it may be longer or shorter due to expanslonor contraction, and therefore the images on the two bands arenon-coincident. I overcome that difficulty by the second step, whichconsists in throwing the slight differences of loss or gain into thespace between each successive picture. so that it is divided over thewhole length of the film between all theprinted pictures.

These registering devices may comprise a pair of oppositely placedwheels or drums having accurately cut sprocket teeth proj ecting fromthe surface of each drum, the two printing belts having each a series ofaccurately punched perforations which are accurately spaced to thesamepitchas the sprocket teeth. The two wheels or drums are preferablydriven from a common shaft through worm or bevel gearing so that theywill rotate in unison and ensure that thetwobelts move forward incorrect register. After passing over the wheels or drums the two beltsare pressed: simultaneously, one

against one face and the other against the other face of the filmto beprinted by a sries of "pairs of rollers between which the belts and thefilm pass, the number of such rollers and the distance the belts andfilm travel together depending on the length of time it is desired tokeep the belts in contact with the faces of the film.

When the. printing belts are made wider than the film each wheel or drummay *be formed with alternating teeth and recesses so that the teeth ofone wheel or drum enter the recesses in the other after passing throughthe perforations in the printing belts. Such-a construction will alwaysbring the pair of belts to the impression point, where one rollerpresses against one face of the film to be printed and the otherpressesagainst the other face. In etfectthey form a pair of smooth-faced drumsor rollers, between which the film to be printed is gripped by theprinting belts which pass over or around one half'of each of the saiddrums. The drums may if desired, be rubber covered to provideslightlyyielding impression pads. The printing belts and blank film maybe both of the same width, in which case the perforations are in theusual margins withinstandard width, and this is the preferredarrangement.

But alternatively the printing beltsfmay be wider than the blank film,and have perforations in the extra margins which therefore entirely missthe film.

In the lattercase the form of interlocking registration sprockets can beused, and reg 1strat1on and pressure begln at the same po1nt.'

Or in the former case registration upon separatedsprockets, higher upthan the impression contact, is efiec'ted.

Pressure contact is effected by two sets of rolls, each roll positivelydriven at same sur face speed as all other parts of the machine, eachgroup having its own worm shaft.

Or pressure contact may be effected between two endless rubber (orother) bands passing over the aforesaid groups of rollers. One group ofrollers and worm shaft is a fixture, the other group and its worm-shaftPerforating the fihn The blank film is non-perforated before printing,and is perforated after printing by either of two methods. In the firstmeth- 061 the positions of the perforations areadjusteol by an operatorand sight control as shown in my specification No. 1,169,079. In

V the second method which is the one preferred, the perforations aremade automati cally after printing, the perforating machine beingcoupled with the printing machine in such manner that the positions ofthe perforations are controlled by the machine- In both methods the lossor gain in length of one band comparedwith the'other is divided betweenthe pictures throughout the whole length of the strip of film. 1

The system described for printing on to blank non-perforated; film fromperforated photo-mechanical imbibition printing belts and then addingthe perforations after printing is novel, and it overcomes the greatdifficulty of loss of register due to expansion or contraction of theblank non-perforated film after printing.

The blank film is drawn or fed forward by the usual means, and isaccurately guided upon each side to and at the impression point, so thatitis passed between the belts and sprocket rollers exactly in the rightposition.

The printing belts may be carried by reels from which they are fed in aforward direction for one print, and rewound in the opposite directionbefore making the next, print, but it is preferred to make them endlessin order that they may run continuously in a forward direction andrepeat printing without rewinding. 7

The belts are supported from sprocket drums which are all driven inunison, and during their passage through the machine are fed with afresh charge of dye to every image of the series, a difierent color foreach printing belt, the dye being preferably fed by a set of ductorrolls which apply it to the images upon the printing belts until theyare sufliciently charged.

When each pair of images reaches the printing point the film to beprinted in mpped or squeezed between them, after which the three bandsare led forward in the machine, still in close contact, for a long orshort dwell period, to allow the dye to be drawn from the printing beltsand completely absorbed into the film surfaces, after which the printingbelts leave the film which then passes to the varnishing machine anddrying room.

Various combinations of colors used only for tinting themono'chromeimage either all over or in parts may be applied in- 0 the?modifications For printing more than two colors the printing operationsare repeated upon the same film from printing belts carrying othercomponent images. I V v Thus four-color pictures can be produced attwooperations bytwo superimposed component images upon each side of thefilm, and three-color pictures can be producedby two inlages upononeside and one upon the other s1 e. I

A single machine operating as two sections following each other, willenable a blank film to enter at one end and emerge from the other end ofthe machine with a four-color or three-' color picture completedthereon. I 7

Between the first and second impressions it is desirable to interpose a.thin layer of absorbent colloid to receive thesecond color and isolateit from the first. This is easily effected by varnishing the-first colorprint with a thin solution of-the colloid and then drying it beforeapplying the second color print.

A combination surface, very suitable for" dye-impression printing by theimbibition process hereinbefore described, can be made by a mixture ofgelatine and acetate-cellulose, or by a mixture of gelatine andnitrocellulose, by using solvents common to both ingredients in makingup the dope from which the film is cast. The mixture can be used as thefilm-material itself, or merely as a facing layer applied to othermaterial. For such combination surface the dye used must be suited toboth ingredients of the film-material.

' 7 What I claim as my invention and desire to protect by Letters Patentis 1. The process of producing a cinematograph or other series oftwo-color positive pictures upon a non-perforatedtransparent film bysimultaneously printing in register on both sides of the non-perforatedfilm by means of two photo-mechanical printing belts 2. The process ofproducing a cinematograph or other series'of two-color positive picturesby simultaneously mechanically printing in register on both sides of anabsorbent' faced unperforated film strip.

. 3. The process of producing a cinematos graph or other series oftwo-color positive pictures upon a non-perforated transparent film whichcomprises the following sequence of operations :--Simultaneouslyregistering exactly opposite to each other a'pair of component imagesupon two photo-mechanical printing belts; then pressing the images andbelts into contact with a strip of transparent film which has noregistration perforations; and keeping all three strips in pressurecontact until the transfer of colors from the belts on to the film iscompleted.

In testimony whereof I have hereunto set my hand this 28th day of March,1929.

JOHN EDWARD THORNTON.

